U4L3

Question 1

what are percentiles

Answer 1

Percentiles - Q1 is the 25th percentile, the median is the 50th percentile and Q3 is the 75th percentile.

Question 2

what is percentile rank

Answer 2

The percentile rank of a scoe is the percentage of scores in its frequency distribution that are equal to or lower than it. For example, a test score that is greater than or equal to 75% of the scores of people taking the test is said to be at the 75th percentile rank.

If the 90th percentile of our class marks is an 82%, then 90% of our class marks are below a mark of 82%.

Question 3

what is a z score

Answer 3

Z-scores - how many standard deviations a data value is away from the mean.

Question 4

negative and positive z scores

Answer 4

Data values with a negative z score are located before the mean and positive z scores are located after the mean.